In a heating ventilation and air conditioning unit (HVAC unit) of an air conditioning device mounted in a vehicle, an evaporator, an air mixing damper, a heater core, and the like are sequentially provided from the upstream side in an air flow channel in a unit case. Temperature-conditioned air having temperature conditioned by those components is selectively blown off by means of a plurality of blow-off mode switching dampers into a chamber from any of a face blow-off channel, a foot blow-off channel, and a defroster blow-off channel that are provided downstream of those components.
The air flow channel is branched into a bypass flow channel and a heating flow channel, downstream of the evaporator, and the heater core is disposed in the heating flow channel. The flow ratio of air flows divided into the bypass flow channel and the heating flow channel can be adjusted by the air mixing damper, and the air flow that has passed through the bypass flow channel and the air flow that has passed through the heater core join together in a region downstream of the air mixing damper, whereby temperature-conditioned air having a set temperature is obtained.
The heater core is installed on a bottom surface side of the unit case so as to run across the heating flow channel, and an entire surface of an upper part of the heater core is supported by upper-part supporting portions for the heater core, which are extended over the entire width in the width direction of the unit case from right and left side surfaces of the unit case. The upper-part supporting portions for the heater core define an air flow channel in a region above the heater core (see, for example, PTL 1, PTL 2, and PTL 3).